1. Field of the Invention
The present invention relates to a flanged ball bearing for use in various precision devices, office automation equipment, etc.
2. Description of the Related Art
It has been customary to manufacture miniature ball bearings and small-diameter ball bearings (hereinafter referred to as "small-size ball bearings") classified according to Japan Industrial Standard by a cutting process which is capable of easily achieving a desired level of dimensional accuracy. However, the cutting process fails to accomplish a greater reduction in the cost of manufacture of such small-size ball bearings.
Japanese laid-open patent publication No. 7-224840, for example, discloses a process of inexpensively manufacturing small-size ball bearings. According to the disclosed process, the outer race of a small-size ball bearing is produced by pressing a steel sheet to shape. For improving the load-resistance capability of small-size ball bearing, it is necessary to increase the thickness of a steel sheet that is pressed into the outer race. However, a steel sheet of increased thickness cannot easily be shaped by a spinning process. If the outer race of a small-size ball bearing is to be made of a steel sheet of increased thickness, then the process of forming the outer race will entail a substantial increase in the cost in order to achieve desired dimensional accuracy of the track of the outer race.